The objectives of this project are to study nitrite and nitrate metabolism in subjects highly susceptible to the development of cancer. The endogenous synthesis of nitrite and nitrosatable compounds in individuals who are at very high risk for gastrointestinal cancer, and the role that endogenous nitrosation reactions may have on the development of gastrointestinal cellular defects previously observed will be investigated. Comparisons will be made with individuals who are highly prone to the development of multiple benign and malignant neoplasms both in the gastrointestinal tract, and in other organs, and with individuals who are at very low risk for neoplasia. Studies also will be carried out to inhibit the formation of endogenous nitrosation reactions in these subjects, and to attempt to inhibit and reduce the progression to malignancy of the cellular defects observed in all regions of their gastrointestinal tract.